Smart Charger vs. MPPT Controller

Suanne · Sep 21, 2011

I'm slowly getting the pieces we need for our egg trailer.  Yesterday I picked up a small used generator.  I know I need to get a smart charger to go between the generator and battery. I also want to make sure that if we include solar panels in the future I've installed compatible components. So, my question is, can an MPPT controller do the work of a 3-stage charger for generator charging.  Or, if/when we get solar, do I need both a smart charger for the generator and an MPPT controller for the solar? Thanks for helping me understand. Suanne

4x4tour · Sep 21, 2011

If I'm understanding your question, a mppt solar charger is used strictly to regulate solar panel DC input, not AC input. My little coleman has a 12v charging receptacle for direct battery charging.  If yours doesnt, you'll need a 3-stage charger, preferably 10 or more amps.  So yes, u need both. My aims1500 watt inverter/10amp charger serves the need AC charging (house, generator etc..) if the solar panel stops working. http://www.theinverterstore.com/the-inverter-store-product.php?model=pwric150012s

Suanne · Sep 21, 2011

Thanks AJ. I got a used Honda eu1000i generator that can directly charge the battery through an accessory cable.  But, I was told that you have to watch it because it could ruin/boil the battery.   So, presumably, it outputs 12v DC ... correct?  I'm trying to get my head around this stuff ... so, please bear with me. Thanks again, Suanne

cyndi · Sep 21, 2011

Suanne, I am glad you're asking these question.  i get so fouled up trying to understand that I don;t even know what to ask! Congrats on the Honda Generator!  What a find!  Theo has an onan and I already miss the Honda that was in the RV at last year's RTR.

Suanne · Sep 22, 2011

So, let me see if I can restate my question in a way that includes my assumptions (which I'm checking to see if they are accurate).  I'm learning. A smart charger, or 3-stage charger will take 110v down to 12v to recharge the battery.  Furthermore, the battery is charged in stages to keep it in good condition and extend its life. A MPPT Charge Controller changes the voltage generated by the solar panels to 12v to recharge the battery.  Furthermore, the battery is charged in stages to keep it in good condition and extend its life. I know there's more to both of these devices than what I written, but I hope I've captured their core purposes. If my descriptions are correct, they seem very similiar.  The only difference being that the smart charger's input is 110v and the MPPT controller's input is the voltage produced by the solar panels. So, given these assumptions, my question is can an MPPT controller handle input of 110v?  I suspect not.  But, it doesn't hurt to ask. Suanne

4x4tour · Sep 22, 2011

So, let me see if I can restate my question in a way that includes my assumptions (which I'm checking to see if they are accurate).  I'm learning. A smart charger, or 3-stage charger will take 110v down to 12v to recharge the battery.  Furthermore, the battery is charged in stages to keep it in good condition and extend its life. A MPPT Charge Controller changes the voltage generated by the solar panels to 12v to recharge the battery.  Furthermore, the battery is charged in stages to keep it in good condition and extend its life.

Exactly!

So, given these assumptions, my question is can an MPPT controller handle input of 110v?

No.

Suanne · Sep 22, 2011

Thanks AJ and Blkjk. Another question. Is there a 3-stage charging device that goes from 12v to 12v (vs. 110v to 12v)?  And, if so, would it be more efficient to charge the battery from the 12v outlet on the generator than going from the 110v outlet, through a typical smart charger? I'm thinking that 12v to 12v would be more efficient than 110v to 12v, just as it's more efficient to use a 12v charger for my laptop than it is to power the laptop through an inverter. But, I don't know for sure ... so, that's why I'm asking. Thanks again, Suanne

4x4tour · Sep 22, 2011

You're generator has a 8amp 12v battery charging plug-in.  Any Kipor or Honda charge cable should work with it  (I made mine with 12 gauge wire and crimp connections).  It doesn't say if its a 3-stage charger, so would just need to keep an eye on battery voltage (i.e. a plug-in cigarette lighter battery level gauge).  http://www.poweredgenerators.com/honda/manuals/31ZT3605.pdf Otherwise, the other choice is a separate AC 3-stage charger.  Depending on your usage will determine the size (amp hours replacement) of the charger needed.  BUT, your generator max AC amp output is 7.5 amps, so you would need a 6amp AC charger, if you went that route i.e. http://www.tackletogo.com/guesporwatba.html   (Guest makes awesome battery chargers) Here's an excellent "tid-bit" on battery charging: <center> <h1>Charging Procedures for Lifeline AGM Batteries</h1></center>There are a lot of different opinions about battery charging and we hope this will help clear up any confusion that our customers have. AGM batteries are still technically a lead acid battery and they charge very similar to a wet cell. Regardless of what some rumors portray, AGM batteries are not as sensitive as once believed. They often get confused with Gel Batteries, which are very sensitive to voltage and they need a special charger. Lifeline AGM batteries can also be equalized to regain capacity if need be (instructions for equalizing is listed below). We also offer very personal service if you would like to reach us by telephone should you have any further questions regarding our batteries. Battery Charging: Charge 1 with voltage-regulated (constant potential) charger. The following charging voltages are recommended for maximum battery life. 3 Stage Chargers <table width="60%" border="1"> <tbody> <tr> <td valign="top">Bulk</td> <td>14.2-14.4 volts</td></tr> <tr> <td valign="top">Acceptance</td> <td>14.2-14.4 volts</td></tr> <tr> <td valign="top">Float</td> <td>13.2-13.3 volts</td></tr></tbody></table> 2 Stage Charger <table width="60%" border="1"> <tbody> <tr> <td valign="top">Bulk</td> <td>14.2-14.4 volts</td></tr> <tr> <td valign="top">Float</td> <td>13.2-13.3 volts</td></tr></tbody></table> Single Stage Charger <table width="60%" border="1"> <tbody> <tr> <td valign="top">Bulk</td> <td>14.2-14.4 volts</td></tr> <tr> <td colspan="2" valign="top">Once the battery is fully charged, remove it from charger.</td></tr></tbody></table> <center> <h1>Battery Equalizing and Deep Discharge Conditioning</h1></center>Charge: Charge with voltage-regulated (Constant voltage) charger. Charge1 @ 15.5 volts for 8 hours. Ã‚Â¹ Avoid overcharging. All batteries must be adequately vented during charging to avoid accumulations of explosive hydrogen gases. Never install or charge in a sealed container or sealed room. Equalizing should only be done when the battery is showing symptoms of capacity loss or from inadvertent deep discharges. In the event equalization is necessary, make sure to go through the normal charge cycle. Once the battery is fully charged, begin equalizing. Note: For 24 volt battery banks, simply take the charge voltages as provided above and multiply by 2. For maximum battery life, a battery must be recharged to 100% capacity. Recharging less than 100% may result in premature battery failure. Lifeline batteries are not covered under warranty if they are not recharged properly. For more information, please refer to our warranty policy. For Inverter/Charger applications: Refer to the Inverter/Charger manual to ensure the correct voltages have been set. Knowing when to recharge: For maximum battery life in deep cycle applications, do not discharge the battery bank below 50%. Continually discharging the bank 100% will shorten the battery life. The open circuit voltages listed below approximates the various States of Charge (SOC). <center> <table border="1" cellpadding="5"> <tbody> <tr> <td>DOD (%) </td> <td>1 hr. Rate </td> <td>8 hr. Rate </td> <td>20 hr. Rate </td> <td>120 hr. Rate</td></tr> <tr> <td>10 </td> <td>12.23 </td> <td>12.62 </td> <td>12.65 </td> <td>12.79</td></tr> <tr> <td>20 </td> <td>12.16 </td> <td>12.51 </td> <td>12.55 </td> <td>12.69</td></tr> <tr> <td>30 </td> <td>12.07 </td> <td>12.39 </td> <td>12.42 </td> <td>12.55</td></tr> <tr> <td>40 </td> <td>11.96 </td> <td>12.25 </td> <td>12.28 </td> <td>12.40</td></tr> <tr> <td>50 </td> <td>11.83 </td> <td>12.11 </td> <td>12.13 </td> <td>12.22</td></tr> <tr> <td>60 </td> <td>11.70 </td> <td>11.96 </td> <td>11.98 </td> <td>12.08</td></tr> <tr> <td>70 </td> <td>11.55 </td> <td>11.79 </td> <td>11.81 </td> <td>11.90</td></tr> <tr> <td>80 </td> <td>11.38 </td> <td>11.59 </td> <td>11.61 </td> <td>11.70</td></tr> <tr> <td>90 </td> <td>11.15 </td> <td>11.32 </td> <td>11.34 </td> <td>11.43</td></tr> <tr> <td>100 </td> <td>10.50 </td> <td>10.50 </td> <td>10.50 </td> <td>10.50</td></tr></tbody></table></center>Please note that these voltages are averages and will vary slightly from battery to battery even of the same rating. They are, however, a good indicator of state of charge and can be used when setting low voltage alarms or disconnects for a Lifeline AGM battery. Other battery types or manufacturers voltage vs. DOD may be substantially different. The data is for newer batteries with relatively few cycles. An older battery will measure a lower voltage for a given DOD. <h3>SOC (%) vs. OCV the battery State Of Charge vs battery's Open Circuit Voltage </h3>An easy method to estimate the State of Charge (SOC) of the battery is by measuring its Open Circuit Voltage (OCV). This measurement should be made after the battery has been at rest for a minimum of four hours with the battery shut off from its charging source and load. The voltage is listed as Volts/cell and for a 12V (6 cell) battery at 25Ã‚Â°C (77Ã‚Â°F). <center> <table border="1" cellpadding="5"> <tbody> <tr> <td>State of Charge (%)</td> <td>OCV per cell </td> <td>OCV per 12V battery</td></tr> <tr> <td>100 </td> <td>2.17 or greater </td> <td>13.0 or greater</td></tr> <tr> <td>75 </td> <td>2.10 </td> <td>12.6 </td></tr> <tr> <td>50 </td> <td>2.03 </td> <td>12.2 </td></tr> <tr> <td>25 </td> <td>1.97 </td> <td>11.8 </td></tr> <tr> <td>0 </td> <td>1.90 or less </td> <td>11.4 or less</td></tr></tbody></table></center> Multiple Batteries: If there is more than one battery in the battery bank, the following guidelines should be used: <table id="battery" width="100%" cellspacing="5"><tbody><tr><td align="left"><li>Always use batteries of identical make, model and with the same manufacturing date. </li><li>Make sure the battery cable is not undersized for the battery system. </li><li>Make sure the battery cables are connected to the terminals correctly. If unsure, professional assistance is recommended </li></td></tr></tbody></table>

oldnjung · Sep 22, 2011

Suanne, Our van has a dual battery system and a 35 gallon fuel tank. I bought a Sears PM (Platinum Marine)-2 battery because it is completely sealed. It advertised at around 60-80 amp hrs, but I planned on 40-50 as a "window". Just plopped it down behind drivers seat and used it for the Edgestar fridge, small fan and recharging phones. Needed to recharge it every morning, but it never got below half charge (12.2 or 12.3 volts). Had a Sears Diehard 3 stage ( 50,10,2 Amp) charger which we plugged into inverter that was plugged into cig lighter. Took off down the road and "voila" . . .45-60 minutes later it was charged. (Did this while idling also). Now I have a Schumacher 3 stage charger (Walmart) with setting for AGM, better controls and higher rate of amps. With the fuel economy of the Prius, you might be able to charge a couple of AGM batteries through the cigarette lighter. I can't afford a solar hookup yet, so I plan on getting at least one more Sears PM2. jb

Suanne · Sep 22, 2011

AJ, Blkjak, and JB ... thanks so much for all of the good information.  I think I'm slowly understanding this stuff. AJ ... I'm going to re-read what you posted and go to those sites you provided links for.  I can tell there's lots of good information there to absorb. I haven't got the battery(ies) yet.  If I can't find a good used AGM deep cycle battery(ies), then I plan to get 2 6v AGM deep cycle batteries and tie them together. Blkjak ... Like you, I was originally thinking about charging the house batteries while driving by connecting them to the starter battery.  But then read somewhere (can't remember where), that an older starter battery will harm a newer house battery, and it will also never completely charge the house battery.  So, I decided against that route.  If that information is incorrect, please let me know. JB ... I think your solution using the inverter/charger combo to charge your house battery is very clever.  I wonder if it has the same pitfalls as noted above.   ... When traveling in the Prius I don't have a house battery, per se.  But I do use the Prius engine (ICE) kind of like a generator to keep my electronics charged up and keep its drive-train batteries in a sufficient SOC in order to run the AC when parked. ... When hauling the fiberglass egg trailer, with the house battery, we use a Camry Solara that's rated for towing (whereas you're not suppose to tow anything with the Prius, unfortunately). Thanks again, Suanne

Suanne · Sep 22, 2011

blkjak said:
i will be getting three agm batteries .... one will be the new starter location battery and the other two will be the rear battery bank; by doing it this way with the relay, i will have three battery's in my battery bank ....

Yes.  I remember reading that thread.  And sorry for misspelling your name too blkjak. Suanne

oldnjung · Sep 22, 2011

I think buying a used battery is pretty risky unless it is significantly cheaper than new, and you can have it professionally tested. However, sometimes people "overbuy" and simply don't use what they bought so I hope you find a bargain.  Solar is great if one can afford it. Also, I'm going to trust the Schumacher XC75 over the 12 volt charger on my Yamaha generator. Check it out on Amazon.com or visit a Walmart. jb

Suanne · Sep 22, 2011

jbandhilda said:
I'm going to trust the Schumacher XC75 over the 12 volt charger on my Yamaha generator.

JB ... I checked out the Schumacher XC75 on amazon.  Nice unit.  I can see why you'd want to use that vs. the 12v charger on a generator.  Thanks for the lead. As far as getting solar panels or an MPPT controller ... both of those are going to have to wait for us as well. Suanne ... getting ready for a little road trip tomorrow

4x4tour · Sep 22, 2011

I don't think you can use anything like the Schumacher XC75 with your 1000 watt (7.5 amp) generator.  Well, I guess you could use the 3 or 5amp setting on it.  But, the higher settings would shut down the generator, I would think. Has anyone else tried something like this?

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